K24 Abstract The overall goals of this K24 application are to provide Maryam Asgari MD, MPH with protected time to serve as a mentor to junior clinician investigators, and to support new scientific aims that will build upon Dr. Asgari's established work on patient-oriented research in skin diseases. Dr. Asgari is a Mohs Surgeon in the Department of Dermatology at Massachusetts General Hospital and an Associate Professor in the Department of Population Medicine at Harvard Medical School. She is the principal investigator of several large patient-oriented research studies, including an NCI-funded R01 of 80,000 Kaiser Permanente Health Plan members previously enrolled in a Research Program in Genes and Environmental Health; an ongoing NIAMS-funded R03 comparing the effectiveness of two commonly used topical agents in the treatment of precancerous skin lesions; and a foundation-funded project comprehensively characterizing acral lentiginous melanomas, a rare melanoma subtype. Dr. Asgari has already successfully served as a research mentor to numerous clinicians in training, and is continuing to mentor multiple individuals ranging from medical students to junior faculty in her new academic environment at Harvard Medical School. This K24 award would come at a critical time in Dr. Asgari's career, as she solidifies her independent research trajectory and seeks to increase her availability to mentor junior investigators. The award will also support a new research investigation that builds on Dr. Asgari's ongoing NIH supported work in cutaneous carcinogensis with a renewed focus on precancerous skin lesions (actinic keratoses). The proposed scientific aims will take advantage of existing data from Dr. Asgari's R01 and R03 awards with actinic keratoses as the outcome measure of interest. This project will allow mentees the ability to use existing datasets to examine novel topics in the risk factors and treatment variation of actinic keratoses.